1. Field of the Invention
This invention pertains to an implant for passing blood flow directly between a chamber of the heart and a coronary vessel. More particularly, this invention pertains to such an implant with an enhanced design for enhanced compliance of a transmyocardial conduit in a coronary vessel.
2. Description of the Prior Art
Commonly assigned U.S. Pat. No. 5,755,682 and PCT International Publication No. WO 98/06356 teach an implant for defining a blood flow conduit directly from a chamber of the heart to a lumen of a coronary vessel. An embodiment disclosed in the aforementioned patent and application teaches an L-shaped implant. The implant is a conduit having one leg sized to be received within a lumen of a coronary artery and a second leg sized to pass through the myocardium and extend into the left ventricle of the heart. As disclosed in the above-referenced patent and application, the conduit remains open for blood flow to pass through the conduit during both systole and diastole. The conduit penetrates into the left ventricle in order to prevent tissue growth and occlusions over an opening of the conduit. 08/944,313 filed Oct. 6, 1997, entitled xe2x80x9cTransmyocardial Implantxe2x80x9d, and filed in the name of inventors Katherine S. Tweden, Guy P. Vanney and Thomas L. Odland, teaches an implant such as that shown in the aforementioned ""682 patent with an enhanced fixation structure. The enhanced fixation structure includes a fabric surrounding at least a portion of the conduit to facilitate tissue growth on the exterior of the implant. This application has the same disclosure as PCT/US 98/17310.
Implants such as those shown in the aforementioned patent and applications include a portion to be placed within a coronary vessel and a portion to be placed within the myocardium. When placing a portion of the implant in the coronary vessel, the vessel is incised a length sufficient to insert the implant. When placed within the coronary vessel, the implant discharges flow axially into the vessel.
When placing an implant, a portion of the coronary artery is dissected. The dissected portion is incised and the vessel portion of the implant is inserted into the lumen. A stay suture secures the artery to the implant. The stay suture is paced around the artery and vessel portion a distanced spaced from the open end of the vessel portion.
The implant is rigid. The vessel is compliant. Since the vessel is radially flexing over time, the compliance mismatch between the vessel portion and the vessel may damage the vessel.
According to a preferred embodiment of the present invention, a transmyocardial implant is disclosed for establishing a blood flow path through a myocardium between a heart chamber and a lumen of a coronary vessel. The implant includes a hollow rigid conduit having a vessel portion and a myocardial portion. The vessel portion is sized to be inserted into the vessel. The myocardial portion is sized to extend from the vessel portion and through the myocardium into the chamber. The conduit has open vessel and myocardial ends on respective ones of the vessel and myocardial portions to define a blood flow pathway within an interior of the conduit between the vessel and myocardial ends. The myocardial portion is formed of a conduit material sufficiently rigid to resist deformation and closure of the pathway in response to contraction of the myocardiurn.
The vessel portion has a radial compliance approximating a radial compliance of the vessel.